1. Technical Field
The present invention relates to three-dimensional computing. In particular, the present invention relates to proton-computed tomography.
2. Background Art
Generating an internal 3D image of an object with proton computed tomography (pCT) starts by firing many protons through the object. Each proton's path (i.e., trace history) is recorded and the collection of all the trace histories are used as input to a computer program that generates the image. Some posit that images generated through pCT will be more effective in proton-based treatments of cancer than images produced through X-rays.
The algorithms that produce images from proton trace histories are complex and involve many stages. The computer memory and speed needed to produce a quality 3D image of an object for which proton-based cancer treatment can be applied (e.g., a human head or pelvis) within clinically meaningful time frames exceeds the capacity of even the most powerful desktop computers available today. Therefore, there is a need for an algorithm to make images from proton trace histories more effectively.
Detectors for pCT in the prior art employ larger bulky plastic cube shaped tubes (such as in Pemler, et al.) with large and bulky photon sensors that require much larger volumes that present problems when mounted on a proton gantry with limited space around the patient. Pemler, et al. describes the possibility to perform radiography with protons and used a single X-Y plane in front of the object being analyzed and a single X-Y plane after. Pemler, et al. also uses vacuum photomultipliers, square fibers, and combinatorial readout. Amaldi, et al. describes a Proton Range Radiography system with an imaging area of 10 cm×10 cm with a stack of thirty thin plastic scintillators. The current pCT detector at Loma Linda uses silicon wafers that are limited in available area (9 cm×9 cm), thus requiring a mosaic of overlapping tiles to achieve large area (27×36 cm). The maximum size now produced of silicon wafers is 10 cm×10 cm. The tiles are shingle overlapped or placed with edges butting, which create dead space in the detector or double layers that require “mathematical removal” during image calculations.
Therefore, there also remains a need for a detector for pCT that eliminates dead space and double layers created by the arrangement of tiles.